Rock bolts in combination with plates through which they pass are used in underground structures such as mines to reinforce the rock. These rock bolts are installed by a rock bolter which drills a bolt hole and then places a bolt therein. When the bolts are held in place by resin, the rock bolter drills the bolt holes and thereafter resin sausages are placed in the bolt holes. The casing of the resin sausage is broken by inserting a bolt into the bolt hole and the resin from the sausage forms a bond between the bolt and the rock. Frequently during drilling the holes are flushed while being drilled to remove chips generated while drilling. Flushing the bolt holes while drilling increases the efficiency of drilling and can enhance the bond between the rock and the bolt inserted therein. Flushing can be accomplished by injecting a fluid into the bolt hole while it is being drilled. Typically, a fluid, such as water or air, is employed for flushing. In either case, the fluid serves to purge the bolt hole being drilled of debris. Preferably, to reduce dust generated by flushing with a gas such as air, small quantities of liquid, such as water, are dispersed in the flushing air. The dispersion of water in the air serves to pelletize the dust.
The resin sausage used for setting the rock bolt is injected into the bolt hole by placing the resin sausage in a resin sausage insertion chamber which is connected to a flexible tube which terminates in a resin sausage inserter. The resin sausage inserter is aligned with the bolt hole and the resin sausage is passed into and through the flexible tube and is directed into the bolt hole by the resin sausage inserter. The resin sausage is provided with a flexible sheet of material which is attached to and surrounds the resin sausage forming a parachute. The parachute maintains the resin sausage in the hole after the resin sausage has been injected into the bolt hole and before the bolt has been positioned therein. The parachute also reduces the amount of gas bypassing the resin sausage as it is ejected from the resin sausage insertion chamber and advanced by the gas through the flexible tube and the resin sausage inserter.
The method described above for injecting a resin sausage into a bolt hole frequently results in the resin sausage not being properly positioned in the bolt hole. On other occasions, the resin sausage prematurely ruptures before a bolt is positioned in the bolt hole. Both of the above problems can result in inadequate bonding between the rock bolt and the hole.
Thus, there is a need for a method which will assure the injection of a resin sausage with greater precision and without premature rupture as well as a system to practice the same.